Real-time Simulation and Visualization using Pre-

calculated Fluid Simulator States

Real-time Simulation and Visualization using Pre-

calculated Fluid Simulator States

Marek Gayer, Pavel Slavík and František Hrdlička

Computer Graphics GroupDepartment of Computer Science and EngineeringFaculty of Electrical Engineering of CTU in Prague

Czech Republic

7th International Conference, Information Visualization, London, July 16-18 2003

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Outline of the presentationOutline of the presentation

Brief introduction to Fluid Simulators and Solvers

Our solution overview– Fluid simulator– Virtual coal particle system– Fluid Simulator State Extension (FSS)

Comparison against data sets Demonstration of results Conclusion and future work

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Fluid Simulators and SolversFluid Simulators and Solvers

For simulation and visualization of various nature phenomena:– Water and liquids– Clouds, smoke– Fire and combustion– Special effects

ACM SIGGRAPH Proceedings(see references in our paper)

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Real-time modeling of fluidsReal-time modeling of fluids

Most often: solving differential equations (e.g. Navier-Stokes)

Real-time fluid simulator and solvers limitations and conditions:

– Low resolution and/or 2D grid

– Simplified physical models and computations

– Code optimization

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Storing results for real-time replayingStoring results for real-time replaying

Results are stored on hard disk, then real-time replayed– Data sets for selected

characteristics– AVI and MPEG files

Our concept:Pre-calculated Fluid Simulator States (FSS)

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Our system overviewOur system overview

Allows dynamic overview of the combustion process

Real-time simulation and visualization (currently using 2D model simplification)

Designed on following key parts– Fluid simulator with FSS extension– Virtual coal particle system– Simplified combustion engine

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Our Fluid SimulatorOur Fluid Simulator

Dividing boiler area to structured grid cell arrays containing:– Velocities– Masses/Pressures

– O2 concentrations

– Temperatures State update Principle of local

simulation

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Virtual coal particle systemVirtual coal particle system Used for both simulation

and visualization of the combustion process

Virtual particle system approach

Simplified combustion and heat transfer computation

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Extending Fluid Simulator with FSSExtending Fluid Simulator with FSS

Simulation is divided into two phases:– Storing phase - fluid simulator states

for each time step are saved on HDD– Replaying phase - simulation runs

accelerated with pre-calculated fluid simulator states

Except first frame, no other data are saved (e.g. particles)

State files are stored in binary files

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Simulation system architectureSimulation system architecture

VisualizationVisualization

InteractionInteraction

Store FullData Sets

Store FullData Sets

Fluid simulatorFluid simulator

Combustion &heat transfer

engine

Combustion &heat transfer

engineParticlesystem

ParticlesystemGrid cellsGrid cells

Store FSSextension

Store FSSextension

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Feature comparison against data setsFeature comparison against data sets

Much less disk requirements (only fluid simulator states are being saved)

Lower disk bandwidth

Better scalability for large grids and/or tasks with many particles

Same or even better acceleration

No seeking and skip frame ability

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Detailed comparison against data setsDetailed comparison against data sets

Store method /Grid size

FSS /20*40

FULL /20*40

FSS /50*100

FULL /50*100

Simulation time 1214s 1230s 5128s 5133s

Write [MB/s] 0.16 8.0 0.3 3.7

Replay time 627s 603s 816s 864s

Read [MB/s] 0.31 14.6 1.9 21.95

AVG Fps 19.1 19.9 16.3 15.4

Disk space GB 0.2 9.4 1.6 19.1

Total acceleration

x 1.9 x 2.0 x 6.2 x 5.9

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Our interactive combustion systemOur interactive combustion system

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Conclusion and future researchConclusion and future research

Concept of Pre-calculated Fluid Simulator States offers:– Acceleration of Fluid Simulator based applications– Much less disk space & bandwidth requirements

compared to using corresponding data sets– Better scalability then data sets

Future research: – Compression state data using GZIP– Testing with very large data sets– Pre-calculated Fluid Simulator States Tree

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Thank you for your attention.Thank you for your attention.

???Do you have any questions ?